1. Field of the Invention
The present invention relates to a speaker system. In particular, the present invention relates to a small-sized speaker system having a very excellent bass-range reproduction capability.
2. Description of the Prior Art
Many attempts have been made for many years to reproduce bass with small-sized speakers. For example, Japanese Patent Laid-Open Publication No. 50-39123 describes a technique for opposing speaker units to each other to synthesize acoustic waves. This publication describes the capability of increasing the sound pressure of bass by synthesizing acoustic waves, which was difficult to implement with previous small-sized speakers.
The technique described in the above publication increases the sound pressure by outputting acoustic waves from the two speaker units in such a manner that the acoustic waves have an identical phase, amplitude, and waveform. Thus, the technique cannot widen a bass reproduction band using the small-sized speakers.
In addition, in order to assist bass reproduction carried out by the small-sized speakers, a technique has been proposed which uses port tubes to increase deep bass reproduction. This technique, however, is disadvantageous in that it may be subjected to wind noise to reduce the sound quality. Further, the conventional technique using port tubes has not been reported to fully widen the bass reproduction band.
As described above, in the field of small-sized woofers, the object to widen the bass reproduction band without reducing the sound quality has not been attained for many years.
The present invention is provided to solve this conventional problem, and it is an object thereof to provide a small-sized speaker system having a very excellent bass-range reproduction capability.
A speaker system according to the present invention comprises: speaker units; and a sound radiation component for guiding acoustic waves radiated from the speaker system to a free space by causing a larger degree of air compression and expansion than in the case where acoustic waves are directly radiated to the free space with the speaker units mounted in corresponding enclosures of the same shape as the speaker units, so that the speaker system has 20% or more lower f0 than in the case where acoustic waves are directly radiated to the free space with the speaker units mounted in corresponding enclosures of the same shape as the speaker units.
Another speaker system according to the present invention comprises: a first speaker unit mounted in a first enclosure; a second speaker unit mounted in a second enclosure; and an intermediate member disposed between the first and second enclosures in such a manner that the first and second speaker units are opposed to each other at a predetermined distance, the intermediate member defining together with the first and second enclosures, a sound radiation component for guiding acoustic waves radiated from the first and second speaker units out to a free space, so that the speaker system has 20% or more lower f0 than in the case where acoustic waves are directly radiated to the free space with the speaker units mounted in corresponding enclosures of the same shape as the speaker units.
In a preferred embodiment, the first and second speaker units are identical.
Yet another speaker system according to the present invention comprises: a speaker unit mounted in an enclosure; a wall member opposed to the speaker unit at a predetermined distance; and an intermediate member provided between the enclosure and the wall member for defining together with the wall member and enclosure, a sound radiation component for guiding an acoustic wave radiated from the speaker unit out to a free space, so that the speaker system has 20% or more lower f0 than in the case where acoustic waves are directly radiated to the free space with the speaker unit mounted in an enclosure of the same shape as the speaker unit.
In a preferred embodiment, the wall member has an acoustic load section in a portion thereof opposed to the speaker unit.
In a preferred embodiment, the sound radiation component has a front cavity defined in a fashion corresponding to a peripheral portion of the speaker unit and a port for guiding an acoustic wave radiated from the speaker unit to the free space, wherein the port has a width in an intermediate portion thereof which is smaller than those of a connection between the front cavity and the port and of an outlet portion thereof and has a planar shape that is asymmetrical with respect to the axis of the port in an acoustic wave guide-out direction.
In a preferred embodiment, a line defining the planar shape of the port is configured by a continuous curve. Alternately, the line defining the planar shape of the port includes at least a straight portion.
According to another aspect of the present invention, a speaker system comprises: a speaker unit mounted in an enclosure; a wall member opposed to the speaker unit at a predetermined distance; and an intermediate member provided between the enclosure and the wall member for defining together with the wall member and enclosure, a sound radiation component for guiding an acoustic wave radiated from the speaker unit out to a free space, wherein at least part of the portion of the intermediate member defining the sound radiation component is comprised of a material having a pressure absorbing characteristic.
According to another aspect of the present invention, a speaker system comprises: a first speaker unit mounted in a first enclosure; a second speaker unit mounted in a second enclosure; and an intermediate member disposed between the first and second enclosures in such a manner that the first and second speaker units are opposed to each other at a predetermined distance, the intermediate member defining together with the first and second enclosures, a sound radiation component for guiding acoustic waves radiated from the first and second speaker units out to a free space, wherein at least part of the portion of the intermediate member defining the sound radiation component is comprised of a material having a pressure absorbing characteristic.
In a preferred embodiment, the material having the pressure absorbing characteristic is a polyurethane foam.
In a preferred embodiment, the polyurethane foam has an expansion ratio between 2 and 80.
In a preferred embodiment, the sound radiation component has a pressure adjustment section provided in at least part of a wall surface thereof.
In a preferred embodiment, the pressure adjustment section is comprised of a surface-treated acoustic material.
In a preferred embodiment, the surface-treated acoustic material is a felt.
In a preferred embodiment, the sound radiation component has a front cavity defined in a fashion corresponding to a peripheral portion of the speaker unit and a port for guiding an acoustic wave radiated from the speaker unit to the free space, and the port has a width in an intermediate portion thereof which is smaller than that of a connection between the front cavity and the port.
In a preferred embodiment, the outlet portion of the port is {fraction (1/20)} to {fraction (1/10)} of a diaphragm in the speaker unit in area.
In a preferred embodiment, the wall member has an acoustic load section in a portion thereof opposed to the speaker unit.
In a preferred embodiment, the material having the pressure absorbing characteristic is partly disposed inside the intermediate portion, and an air portion is defined between the material and an inner wall member of the intermediate member.